According to a recent post, increased engine oil consumption due to bore scoring is not covered under the extended warranty. Unless it flat out breaks and no longer runs, they don't cover it. I am not sure how valuable that is as a warranty.

 

My sentiments exactly - I also am an advocate for Bore Scope Inspecting no matter the circumstances.
I had PPI on 2 997S models(2006 & 2007) last year and both failed Grooov-scope Inspection horribly. One had cracked cylinder.

 

These threads scare the crap out of me. Especially the claims that 30% of all 997s will eventually perish due to bore scoring.

I did not get a bore scope during my PPI for my 2005 base with 38k miles two months ago, but I had one done after I purchased as part of the prep for installing the IMS Retrofit kit. The shop noted “nothing significant; only minor scruffs, which look normal.”

However, the scope was only from the top and not from the sump, so they would have missed anything at the very bottom of the cylinder due to the piston being in the way. Also, I stupidly didn’t request photos, so I really have no ability to review myself or get a second opinion.

I just have to hope that I’m good for now and utilize good driving habits like letting the car and oil get up to temp before hard driving. I’m looking into a low temp thermostat based on recs here, but otherwise I think I just need to not stress so much about it because it’s compromising my enjoyment of the car.

 

A scope done from the sump is preferred as the scoring tends to begin at the bottom of the cylinders. Don't live in fear of this. Start the car and drive off, don't let it sit idling to warm up. Keep the RPMs under 3k until oil reaches operating temps, then drive the snot out of it as it was intended to be driven!

 

No, not your post at all, was meant to be directed at the OP. He used some wording that made it sound like he thought it may not be real or not common enough to worry about.

 

Yup both were 997.1's 2007 and 2008 models. I was ready to buy and subject to clearance on bore scoring and both came back with scoring on them. And the weird thing was both cars didn't have any of the symptoms everyone is mentioning like the engine clicking noise, left exhaust pipe with residue, exhaust smoke, or even needed to add oil. Both of the sellers were shocked their car had bore scoring on it. The seller even discounted the car for $20K but I don't want to deal with it so it was a no go for me. From what I heard both car sold in the auction now and someone will probably end up with those 2 cars with scoring and not know it.

 

Ed99 .
Were both cars Ss (3.8)? How many miles on each? Did you see the pics, ie how bad were they - were they mistaken for scuffing perhaps?
Not to say you should have bought the cars, just curious.

 

Why would that be scary with a 911?

100% of all 911S with magnesium cases have head studs pulling out of the case. 100% of all 911SC and Carrera have Dilavar head studs that break. Those all need full strip down and rebuild to fix. 100% of all 993 will need to have secondary air injection system rodded out or a valve job. A very large number of 996 will need IMS upgrade or fix.

Those problems do not stop people from paying outrageous prices for the air cooled porsches or to buy and enjoy the 996? Buy it, drive it, enjoy it, and fix it. Just remember that nobody ever promised you that owning a Porsche is going to be cheap. It's not.

 

There is a massive difference between spending a couple grand for an IMS bearing upgrade and spending $25-35k for an engine rebuild due to bore scoring. These things are remotely comparable problems.

 

Having rebuilt my 05 997S engine due to bore scoring, I’ve been interested in finding out the root cause of the problem. I’ve studied much anecdotal evidence on the internet as well as my own observations when stripping and rebuilding mine. I’m now convinced it’s to do with the open deck cylinder design which leads to a stretching out of the cylinder at the thrust face. This gives an egg shaped cylinder at the top and hence a kink in the thrust face in the direction the piston travels. This causes the oil film to break down between piston and cylinder leading to scoring.

The graph below shows the lateral force imparted on the cylinder by the piston, peaks about 20 degrees after TDC in the direction of the thrust face.


When an engine warms up the cylinder temperature can overshoot the normal running temperature before the thermostat opens. If during this time the engine is run at full throttle (at maximum torque speed) and hence maximum lateral piston load, the cylinder can stretch out on the thrust face due to the lowered yield strength caused by the cylinder wall temperature overshoot. This is why a low temperature thermostat helps but most importantly why the car shouldn’t be driven at full throttle before it is fully warmed up and temperatures have reached equilibrium.

I’ve also looked at the various M96/M97 engines to see whether this can explain why the 3.8 is worst affected and the 2.5, 2.7 and 3.2 aren’t. The table below shows the block dimensions of all the non GT and turbo M96/M97 engines. The biggest difference is the cylinder wall thickness, this will have a linear affect on the tensile stress seen by the cylinder wall in the zone where it stretches. The bore diameter will influence the force exerted on the piston crown and hence the lateral force and tensile stress in the cylinder wall as a square function. When both of these effects are quantified it can be seen that the 3.4 and 3.6 engines have about 94% of the peak stress seen by the 3.8 engine and the 2.5, 2.7 and 3.2 engines are at less than 75% hence giving them much better protection from cylinder distortion.



The bottom line is Porsche have just pushed the 3.8 and to a lesser extent the 3.6 and 3.4, too far while still maintaining the 118mm cylinder spacing.

So to answer the OPs original question with a sympathetic warm up procedure, it is possible to avoid scoring.

 

I've said it before, and I'll say it again: I believe most, if not all, .1 cars will have some level of "scuffing" or "streaking" visible when scoped.

I had my #6 cylinder scoped from the top (I realize that doesn't paint the full picture) during my PPI and it had signs of scuffing. I consulted with the shop that did the PPI, as well as my Indy here locally, and decided to take the risk and went through with the purchase. That was 3+ years and ~13k miles ago, and my car still runs great. It's my belief that if you take the appropriate precautions (let the car warm up properly before spirited driving, frequent oil changes with a high quality synthetic oil, use a top-tier fuel, install a low-temp thermostat, etc.) that you can drive one of these cars for years and many miles trouble free before symptomatic bore scoring presents itself.

I was reading through the other thread discussing annual mileage on these cars. It seems as though most people, myself included, have another daily driver and are putting 3k-4k miles on our 997's annually. So say for example, you bought a 997.1 and the engine 'only' had 30k-40k miles left before needing a rebuild, that could be 10+ years from now depending on how often you drive your car.

If you're shopping for a .1 car and are looking for streak-free/scuff-free cylinders, you'll be shopping for a while. I'm certainly not suggesting that potential buyers bury their heads in the sand, I'm just trying provide some perspective.

 

I don't know. A friend of mine spent $15K replacing his 996 engine due to a failed IMS ... it's pretty comparable to him.

 

Yes, but you can proactively upgrade the IMS bearing for a couple grand and no longer have to stress about it. You can’t proactively eliminate the bore scoring issue altogether.

 

Yup both are S models under 50k miles on them and I saw many pics and confirmed from the person conducting the bore scoring. Definitely not scuff marks.

He also told me out of 10 scopes he does in the last 2yrs, 8/10 cars has bore scoring on them. Definitely worth the $350 spent getting it checked out.

 

I have a 997.1 that was converted to a track rat for DE, third rad, low temp therm, oil fed IMS, lasted 6 seasons and punched a rod through the starter. Upon dissembling the IMS was perfect, but 997 rod bolts are a known failure point. It now has a replacement from a convertible that met a utility pole. I converted it back to a street car and bought a 996 GT3 prepared track car. The 997 is a great car but the engine is not for anything other than just normal driving and the occasional flog.